The long-term goal of this project is to develop a theoretical account of how children acquire access to segmental speech structure given that there are no clear landmarks for that structure in the acoustic signal. The approach taken assumes that adult listeners access that structure by applying language-specific strategies for perceptual organization to linguistically relevant acoustic properties. Specifically the model explored suggests that children initially organize the acoustic speech signal as a spectrally unitary whole according to universal strategies, and then, through early language experience, learn to organize the dynamic components of the speech signal in language-specific ways, and to weight in phonetic decisions certain non-dynamic, spectro-temporal properties that are phonetically informative in the native language. In turn, it is hypothesized that one or both of these learned strategies facilitates recovery of segmental structure. Six specific aims derived from this model wilt test the hypotheses that: 1. children initially weight dynamic signal components (i.e., formant movements) greatly because these components generally adhere to principles of Auditory Scene Analysis;2. the acquisition of mature speech perception involves changes in the perceptual organization of dynamic signal properties, a process termed Developmental Perceptual Reorganization;3. young children are more strongly obliged than adults to organize speech-like signals as spectrally unitary signals;4. static properties provide an advantage over dynamic properties in the recovery of segmental structure;5. developmental changes in speech perception and in sensitivity to segmental structure arise due to early experience (i.e., before school age) with a native language, rather than from other factors (i.e., general auditory development or literacy instruction);and 6. children's gestural organization for speech production changes as they acquire experience with their native language. The data collected should advance our understanding generally of how listeners recover segmental structure from the acoustic signal. Clinical significance will derive from this work by helping us understand what we should be doing to promote spoken language development in children with communication problems.